Automatic reclosing circuit breaker



Oct. 20, 1953 A. w. EDWARDS 2,656,433

AUTOMATIC RECLOSING CIRCUIT BREAKER Filed Sept. 3, 1949 Insulation Fig.l.

Fig.2.

84 as ea I0 I 6 1 80 I V/ 76 I x 14 Fig.3. 4o 92 9 6 '4 9o 94 9B 44 IO I2 WITNESSES: INVENTOR W AndrewW.Edwords.

Patented Oct. 20, 1953 AUTOMATIC RECLOSING CIRCUIT BREAKER Andrew W. Edwards, East McKeesport, Pa., as-

signor to Westinghouse Electric Corporation, East Pittsburgh, Pa., a corporation of Pennsylvania Application September 3, 1949, Serial No. 113,933

11 Claims. 1

This invention relates to automatic reclosing circuit breakers generally, and more particularly to such breakers having diilerent circuit opening times on closely successive operations.

Present practice on small automatic reclosing circuit breakers operating on sustained overloads is to permit the first one or two circuit opening operations of the breaker to occur substantially instantaneously upon the occurrence of the overload, and to impose a time delay means, such as an oil dashpot, to delay subsequent opening operations, all for the purpose of coordinating with fuses to permit the latter to isolate the fault. With such devices a time ratio of instantaneous to time delay operation is obtained on the order of 1 to 5.

One object of this invention is to increase the time delay obtainable on time delayed operations of a breaker of the type described and thus enable better coordination of such breakers and fuses.

A more particular object of this invention is to provide in a breaker of the type described, hydraulic time delay means for the delayed operations of such a breaker, with a novel arrangement for transforming at least part of the energy put into such hydraulic means into a mechanical braking action which is eilective to substantially increase the time delay period.

These and other objects of this invention will become more apparent upon consideration of the following detailed description of a preferred embodiment thereof, when taken with the attached drawing, in which:

Figure 1 is a substantially central longitudinal section through an automatic reclosing circuit breaker embodying this invention;

Fig. 2 is an enlarged partial longitudinal section through a part of the breaker shown in Fig. 1; and

Fig. 3 is a view similar to Fig. 2 but showing a modified form.

The circuit breaker shown on the drawing to illustrate one application of this invention is similar to that disclosed in the copending application of J. M. Wallace and J. K. Kraft, Serial No. 718,942 on Circuit Interrupters, filed December 28, 1946, now Patent No. 2,575,738, November 20, 1951, and assigned to the same assignee as this invention.

This particular type of circuit breaker is mounted in a metal tank 2 which is preferably lined over the bottom and side walls by an insulating liner 4, which may be of fiber or the like. The circuit breaker tank 2 has an open top adapted to be closed by a cover casting 6,.

The circuit breaker contacts and contact operating mechanism are all supported from cover casting 6, with the contacts and certain of the operating mechanism extending into tank 2 and being supported from the cover casting as by the insulating supports 8 (only one of which is shown). The supports 8 are secured to the interior of cover casting 6 and are attached at their lower ends to a top casting In for a solenoid coil I4 which is held in place between casting l0 and a bottom supporting plate [2. Casting I0 and supporting plate l2 may be secured together in any desired manner (not shown). A pair of arc extinguishing structures [5 are supported from bottom supporting plate I2, with a stationary contact l6 being mounted on each of arc-extinguishing structures IS.

The stationary contacts l6 are adapted to be electrically connected in the closed circuit position of the breaker, by a bridging contact l8 mounted on a contact-actuating rod 20, which extends upwardly through aligned openings in supporting plate 12, solenoid coil l4, and casting l0. At its upper end, contact-actuating rod 20 is connected by links 22 of insulating material, such as fiber, to one end of a pair of levers 24 and 26 by a common pivot pin 28. Lever 24 is of channel form and is adapted to receive an upper portion of lever 26, with lever 24 being pivotally mounted in pivot recesses 30 formed on a supporting bracket 32 which is secured to cover casting 6 as by screws 34. Lever 26 is adapted to be held at the position shown in Fig. 1 by a coil tension spring 36 having one end secured to lever 26 and the other end anchored to cover casting 6, with the spring being tensioned. Since lever 24 is of channel form, relative pivotal movement of levers 24 and 26 about their common pivot pin 28 in a direction towards each other is limited by engagement of lever 26 in the bight portion of lever 24. In order to limit the relative pivotal movement of levers 24 and 26 apart, lever 26 has an integral hook-shaped portion 38 which projects through a slot in the bight portion of lever 24 to overlie the top thereof.

Solenoid coil [4 has its central opening provided with a dashpot sleeve 40, preferably of an insulating material such as fiber or a synthetic resin, for receiving the solenoid core 42 in a piston-like manner. An actuating sleeve 44 is threaded into an upper opening in solenoid core 42, and extends upwardly through the coil and through casting l0, being provided with a flange 46 at its upper end just above the top of casting ID. A coil compression spring 48 is positioned on contact actuating rod 253 and reacts between core 42 and a pin 4% on contact-actuating rod 29.

The circuit through the circuit breaker shown on the drawing extends from one insulator bushing 43 mounted on cover casting 6 by way of a conductor 45 to one of the stationary contacts It. In the closed circuit position of the breaker, the circuit continues across bridging contact is to the other stationary contact [6, thence by a conductor 4'! to solenoid coil. I4, and from there a conductor 49 extends to the other bushing (not shown) mounted on cover casting, 6. It will be apparent then that solenoid coil i4 is in series circuit relation with the circuit breaker contacts so that when the current in the circuit exceeds a predetermined value, coil [4 will at tract its core 42 upwardly. Such initial upward movement of solenoid core 42 does not, however, separate bridging contact [8 from stationary contact it, inasmuch as these contacts are held in engagement under pressure by spring 3 3 located in the cover casting.

It will be observed that contact pressure spring 38 acts through lever 26 on a line which lies below the pivot point of lever 24 on bracket 32-, so that there is a resultant force in a direction biasing contact actuating rod downwardly to exert pressure on bridging contact 18 holding it in engagement with fixed contacts 16. Accordingly, solenoid core 42 initially moves upwardly without movement of contact actuating rod 20, but this relative movement compresses coil compression spring 43. Such upward movement of core 1-2 continues until spring 48 is compressed an amount sufiicient to overcome the component of contact pressure spring tending to keep the contacts closed, or until flange 46 on contact actuating sleeve 44 engages the collar on contact rod 29. In either case, bridging contact it? will then be moved away from the fixed contact it to open the circuit, and this movement will be accelerated by expansion of spring 48, and by the fact that the downward component of contact pressure spring 36 decreases as contact rod 26 moves upwardly because its line of action approaches the pivot point of lever 24 on bracket 32 as the contact rod 20 moves upwardly. Levers 24 and 25 are designed so that they will not be moved into engagement upon upward movement of contact actuating rod 28 until the point of attachment of contact pressure spring 38 to lever 26 substantially coincides with the pivot point of lever 24 on bracket 32. At this point, it will be observed that contact pressure spring 33 has substantially no component or" force in a direc tion tending to reclose the contacts, and the design should be such that this spring then exerts no reclosing force component or at least substantially no such force component. Accordingly, as soon as this oncenter point of spring is attained, there will be substantially no force tending to oppose opening of the contacts, and this point is reached in response to relatively short movement of contact rod 20. Inasmuch as solenoid core moves in dashpot sleeve 40 in a piston-like manner, its rate of movement when attracted by coil M will be determined upon whether or not the upper end of sleeve 40 is open or closed. If the upper end of sleeve 40 is open, it is obvious that upward movement of core 42 will be unimpeded and that the contacts will be separated substantially instantaneously following the occurrence of current flow in the circuit above a predetermined value. On the other hand, if the top of sleeve 40 is closed, then upward movement of core 42 will be much slower due to the necessity of displacing liquid trapped in the upper portion of sleeve 40 through the relatively small clearances between the core 42, actuating sleeve 44 and the parts in which they move.

As soon as the arc has been extinguished by arc-extinguishing structures I5 and the circuit thus interrupted, solenoid coil l4 will no longer attract its core 42 so that bridging contact [8 will be free to move downwardly due to the force of gravity, and any slight downward component which may then be exerted by contact pressure spring 38. Such downward movement of bridging contact i 8 also will move core 42 downwardly through the. medium of spring 48, and this movement may be quite fast if the upper end of dashp'ot' sleeve 40 is opened, or may be much slower if the upper end of this sleeve is closed. In any case, the rod 20' and other parts will eventually move downwardly sufliciently to cause the line of action of contact pressure spring to move below the pivot point of lever 24 on bracket 32 to thereby increase the downward force component due to this spring so that the final part of contact closing movement will be accelerated.

In order to provide a means for controlling the timing of closely successive circuit opening and closing operations, there is provided on support casting In a counting cylinder 52, supported in an opening in casting l0 and having a counting piston 54 mounted in the cylinder. The bottom of counting cylinder 52 is closed except for a small fluid inlet opening 56 controlled by a ball check valve 58 which permits flow of fluid through opening 55 solely inwardly of cylinder 52. A reduced area extension 60 is provided at the top of counting piston 54 and it has a plurality of integral ratchet projections 62 thereon, which are preferably circular in form, and at the extreme upper end an actuating extension 64 is provided on the counting piston, for a purpose which will be hereinafter referred to,

The counting piston 54 is adapted to be actuated by an operating lever 66 pivotally mounted at one end as at 61 on supporting casting l0, and has a nose 68 at its other end which is split to receive contact actuating rod 28, and rests on flange 46 of actuating sleeve 44. Operating lever 36 is normally biased in a clockwise direction as viewed in Fig. 1 by a spring 69 which is stressed between supporting casting i0 and lever 66 and maintains the nose 68 of the lever in engagement with flange 46.

Operating lever 66 carries a pivoted pawl 10 normally biased to the position shown in Fig. 1 by a spring 12. It will be observed that counting cylinder 52 has an opening in the vicinity of pawl 10 so that when the outer end of operating lever 66- is raised, pawl '10 will move into the opening to engage one of the ratchet portions 62 of the counting piston.

Dashpot sleeve 40 in solenoid coil l4 communicates at its upper end with an annular passage 14 formed between the opening in casting l0 and actuating sleeve 44, and this passage in turn communicates with a hollow chamber #6 in casting ID, with the latter having an outlet 18 to the exterior of the casting.

It will be apparent that when the circuit breaker operates to interrupt the circuit in the manner previously described, the outer end of operating lever 66 will be raised by flange 46 when solenoid core 42 moves upwardly, to thus cause pawl 10 to engage the uppermost ratchet portion of counting piston 54 and carry the piston upwardly a predetermined amount while fluid is drawn into the lower end of counting cylinder '52. Upon reclosing of the contacts, operating lever 56 will return to its original position and pawl it will be withdrawn from engagement with counting piston 52, but the latter will remain at the point to which it was advanced for a predetermined time because it is prevented from returning due to the liquid drawn into the lower end of counting cylinder 52. However, if the circuit breaker remains closed following a first circuit opening and closing operation, counting piston 54 will eventually reset to it original position, as the liquid drawn into the lower portion of counting cylinder 52 will slowly escape through the relatively small clearance between cylinder 52 and its piston 54. It will be observed that since reduced extension 60 of counting piston 54 is located in the passageway I6, is for fluid displaced by movement of solenoid core 42, that such initial circuit opening and closing will occur substantially instantaneously since extension 60 is small enough so that movement of fluid displaced by core 42 through such passageway is substantially unimpeded.

Should the circuit breaker reclose the first time on an overload, it will immediately attempt to reopen the circuit and since counting piston 54 has not had time to return to its original position, pawl will engage the next lower ratchet portion 62 to raise piston 54 a further amount suflicient to bring the piston 54 itself to a point where it blocks fluid outlet opening 18. Ac-

cordingly, upon the second reclosing operation,

downward movement of solenoid core 42 will be much slower than on the first reclosing due to the fact that counting piston 54 has closed the upper end of dashpot sleeve 40. After such a second circuit opening and reclosing operation, the counting piston 54 may again reset to its original position if the breaker does not immediately reopen. However, if the fault is still present on the circuit when the breaker recloses the second time, it will again attempt to open the circuit, but this time opening of the contacts will be delayed because cf the presence of counting piston 54 at the position where it closes fluid outlet opening 18.

The purpose of having one or two substantially instantaneous circuit opening operations followed by time delay circuit opening operations is to coordinate with fuses so that the fuses, being relatively slow acting, will not blow during the instantaneous operating cycles of the circuit breaker, thus permitting self-clearing faults to remove themselves from the circuit. On the other hand, if the fault persists until the third closely successive circuit opening operation of the breaker, it is desired then to cause the fuse on the faulted branch of the circuit to blow and thus isolate the faulted branch of the circuit so that upon the third operation the fault will have disappeared from the breaker circuit. While fuse characteristics may be generally characterized as having substantial time delay before blowing, especially in the range of light overloads, nevertheless various types of fuses vary considerably in the amount of such delay. Consequently, in order to effectively coordinate with all types of fuses, it is desired that a maximum delay be incorporated, for example on the second or third breaker opening operation. It has also been found that a movement resisting device or retarding means such as the dashpot herein illustrated, and others of 6 a hydraulic, mechanical or electrical character do not have sufficient time delay as to make coordination with all types of fuses possible. Accordingly, in accordance with this invention, there is provided a mechanical braking device which is effective at the same time as the dashpot action for imposing additional delay before separation of the circuit breaker contacts occur.

In order to actuate the mechanical braking arrangement, a bleeder opening 80 is provided through the top wall of passage 16 in casting l0, communicating with a brake cylinder 82 mounted thereabove on casting It). A brake piston 84 is mounted in cylinder 82 and it has an extension 86 terminating in a friction brake portion 88, positioned below flange 46 on actuating sleeve 44. It will be apparent that when counting piston 54 block escape of fluid displaced by core 42 in its upward movement, a considerable pressure will be built up in dashpot sleeve 4i) and passage 16, which will be communicated to brake cylinder 82 and its piston 84, to thus move the brake portion 88 into pressure engagement with the outside of actuating sleeve 44, and exert a frictional braking action retarding upward movement of this sleeve and solenoid core 42. It has been found that the time delay may be extended at least by the inclusion of such a mechanical braking arrangement, and even greater time delay may be obtained depending of course on the size of the brake piston and cylinder, and other elements of design.

A modified mechanical braking arrangement is disclosed in Fig. 3 wherein opening 80 from passage 115 communicates with the interior of a flexible bellows 90 having one end of a brake lever 92 resting on top of the bellows. Brake lever 92 is pivotally mounted at $4 on support casting l0 intermediate its ends, and has the other end thereof forming a frictional brake portion 98. A spring 96 biases brake lever 92 in a counter-clockwise direction as viewed in 'Fig. 3 to cause release of brake portion 98 from the outside surface of actuating sleeve 44. This form of the invention operates in much the same fashion as that described above and shown in Fig. 2, in that pressure in passage 16 when counting piston 54 closes outlet opening 18, caused by upward movement of core 42, is exerted within bellows causing it to expand upwardly and thus rotate brake lever 92 in a clockwise direction when the pressure in passage I6 is sufficient to overcome the bias of spring 96, to cause its brake portion 98 to engage the outer surface of actuating sleeve 44 under pressure. Since the pressure in passage 15 is dependent on the cur- 'rent in solenoid coil 14, operation of brake 98 will be effected only when opening 18 is closed 60 land the current in coil I4 is at least of a suffierations upon the completion of a predetermined number of such operations.

Such means are dis closed in the previously mentioned copending application and comprise generally one toggle lever I00 having a slotted end receiving a supporting pin I02 mounted in cover casting 5, and

being surrounded by a coil compression spring I04 reacting between a shoulder at the outer end of toggle lever I00 and the cover casting, to normally bias lever I00 outwardly or to the left as viewed in, Fig 1 Toggle lever I is, however, connected with a toggle lever I08 as by a knee pivot I06, with toggle lever I08 in turn pivotally supported on the cover casting by a. pivot pin IIO. Toggle lever I08 has a handle extension protruding from an opening in the cover casting to normally lie beneath an integral hood portion I I3 in engagement with an adjustable stop screw H 5. At this position or" the toggle levers and handle, it will be observed that the knee pivot I06 of the toggle levers is positioned at a point below a straight line connecting the toggle lever pivot supports H0 and IE2, so that spring I04 acts to maintain handle II2 in engagement with stop screw I I6.

The contacts may be opened by engaging handle H2, as by the hook-eye portion H4, and pulling it downwardly in a counterclockwise fashion as viewed in Fig. l to thus move the knee pivot I06 of the toggle members upwardly- The knee pivot pin I06 of the toggle levers is extended beyond these levers to underlie one edge of lever 24, so that when the handle is pulled downwardly and pivot pin I08 rises, it will engage lever 24 and move it upwardly thus opening the contacts, and they will be held open because toggle levers I00 and I08 will be held at this overcenter position by spring I04. Moreover, the contacts may be manually closed by moving handle I I2 in the opposite direction back to the position shown in Fig. l of the drawing where knee pivot I06 is moved back over center and the toggle levers I00 and I08 are maintained by spring I04 at the position shown. This permits reclosing of the contacts in the manner previously described.

In order to automatically terminate a series of closely successive circuit opening and closing operations, it will be observed that toggle lever I00 has an extension H8 overlying actuating extension 64 of counting piston 54, so that when the latter has been advanced an amount corresponding to a predetermined number of closely successive opening and closing operations, for example three or four such operations, extension 64 will engage toggle lever extension I I3 and move it and toggle knee pivot I06 upwardly overcenter, whereupon toggle spring I04 will move bridging contact I8 to its open position and hold it there. At the same time, handle II2 will be moved down to project beneath hood II3 and thus indicate that the breaker contacts are locked open. Of course, following such automatic lockout operation, the contacts can be reclosed manually in the manner described above.

As in the previously mentioned copending application, the circuit breaker may also include a lightning arrester I connected between conductors 49 and 47 to shunt surge currents across opcrating coil I4. Except for the particular improvement pointed out above, the circuit breaker shown on the drawing is identical with that in the previously mentioned copending application, and accordingly for more complete description thereof, reference is hereby made to such application.

It is believed apparent from the foregoing that this invention provides in an automatic reclosing circuit breaker of the type which operates in any series of closely successive circuit opening operations in an instantaneous fashion on the first one or two operations, and thereafter operates to open the circuit only when a time delay period is interposed between the, occurrence of the overload condition and actual separation of 8 the contacts, with means for obtaining increased time delay over that which heretofore has been possible in a manner providing for mechanical friction braking action on a part movable with the overload responsive means.

Having described a preferred embodiment of this invention in accordance with the patent statutes, it is desired that the invention be not limited to this particular structure inasmuch as it was previously pointed out that it could be employed with other types of circuit breakers, and even to devices other than circuit breakers. Accordingly, it is desired that this invention be interpreted as broadly as possible in accordance with the spirit and scope of the following claims.

I claim as my invention:

1. An automatic reclosing circuit breaker comprising separable contacts, means having a part movable a predetermined distance in response to overloads on the circuit before automatically causing separation of said contacts to open the circuit, means responsive to a circuit opening operation by said breaker for automatically closing said contacts, and time delay means responsive to a predetermined operation in any series of closely successive operations for delaying a closely succeeding operation of said overload responsive means and thus delaying separation of said contacts, said time delay means comprising a movement resisting device actuated by said movable part of the overload responsive means and braking means receiving energy from said movement resisting device for exerting a braking action and positioned to exert a direct braking action on said movable part of the overload responsive means.

2. An automaticv reclosing circuit breaking comprising separable contacts, means having a part movable a predetermined distance in response to overloads on the circuit before automatically causing separation of said contacts to open the circuit. means responsive to a circuit opening operation by said breaker for automatically closing said contacts, time delay means responsive to a predetermined operation in any series of closely successive operations for delaying a closely succeeding operation of said overload responsive means and thus delaying separation of said contacts. said time delay means com prising a dashpot which is actuated by said movable part of the overload responsive means, and hydraulically actuated braking means connected with said dashpot and positioned to exert a direct braking action on said movable part of the overload responsive means.

3. An automatic reclosing circuit breaker comprising separable contacts, means having a part movable a predetermined distance in response to overloads on the circuit before automatically causing separation of said contacts to open the circuit, means responsive to a circuit opening operation by said breaker for automatically closing said contacts, time delay means responsive to a predetermined operation in any series of closely successive operations for delaying a closely succeeding operation of said overload responsive means and thus delaying separation of said contacts, said time delay means comprising a dashpot the movable part of which is said movable part of the overload responsive means, and hydraulically actuated mechanical braking means connected with said dashpot so as to be actuated by fluid pressure built up in said dashpot by movement of said movable part to separate said contacts, and said braking means having a frictional braking member operated into pressure engagement with said part of the overload responsive means upon actuation of said braking means.

4. An automatic reclosing circuit breaker comprising separable contacts, means having a part movable a predetermined distance in response to overloads on the circuit before automatically causing separation of said contacts to open the circuit, means responsive to a circuit opening operation by said breaker for automatically closing said contacts, means responsive to a predetermined operation in any series of closely successive operations for delaying a closely succeeding operation of said overload responsive means and thus delaying separation of said contacts, said time delay means comprising a dashpot which retards said movable part of the overload responsive means during movement to separate said contacts, and hydraulically actuated me chanical braking means having a piston and cylinder connected with said dashpot so as to be actuated by fluid pressure built up in said clashpot during actuation thereof, and said piston having a frictional braking member operated into pressure engagement with said part of the overload responsive means upon actuation of said braking means.

5. An automatic reclosing circuit breaker comprising separable contacts, means having a part movable a predetermined distance in response to overloads on the circuit before automatically causing separation of said contacts to open the circuit, means responsive to a circuit opening operation by said breaker for automatically closing said contacts, means responsive to a pre determined operation in any series of closely successive operations for delaying a closely succeeding operation of said overload responsive means and thus delaying separation of said contacts, said time delay means comprising a dashpot which is actuated by said movable part of the overload reponsive means, and hydraulically actuated mechanical braking means having a bellows connected with said dashpot so as to be actuated by fluid pressure built up in said dashpot during actuation thereof, and said bellows having a frictional braking member operated into pressure engagement with said part of the overload responsive means upon actuation of said braking means.

6. An automatic reclosing circuit breaker comprising separable contacts, means having a part movable a predetermined distance in response to overloads on the circuit before automatically causing separation of said contacts to open the circuit, means responsive to a circuit opening operation by said breaker for automatically closing said contacts, and time delay means responsive to a predetermined operation in any series of closely successive operations for delaying a closely succeeding operation of said overload responsive means in a contact separating direction and thus delaying separation of said contacts, said time delay means comprising a mechanical brake positioned to directly frictionally engage said movable part of the overload responsive means during motion in a contact separating direction only.

7. An automatic reclosing circuit breaker comprising separable contacts, means having a part movable a predetermined distance in response to overloads on the circuit before automatically causing separation of said contacts to open the circuit, means responsive to a circuit opening operation by said breaker for automatically closing said contacts, means responsive to a predetermined operation in any series of closely successive operations for delaying a closely succeeding operation of said overload responsive means and thus delaying separation of said contacts, said time delay means comprising a hydraulically actuated mechanical brake positioned to directly frictionally engage said movable part of the overload responsive means during movement in a contact separating direction.

8. An automatic reclosing circuit breaker comprising separable contacts, means having a part movable a predetermined distance in response to overloads on the circuit before automatically causing separation of said contacts to open the circuit, means responsive to a circuit opening operation by said breaker for automatically closing said contacts, means responsive to a predetermined operation in any series of closely successive operations for delaying a closely succeeding operation of said overload responsive means and thus delaying separation of said contacts, said time delay means comprising a mechanical brake positioned to directly irictionally engage said movable part of the overload responsive means, and means for transmitting energy from said movable part of the overload responsive means to exert its braking action during movement thereof in a contact separating direction.

5. An automatic reclosing circuit breaker comprising, separable contacts, means operabie to automatically cause separation of said contacts in response to overloads on the circuit, means re sponsive to a circuit opening operation for auto matically closing said contacts, dashpot means including movable valve means operable to effect a predetermined delay in certain operations in a sequence of operations of said overload responsive means, and time delay means operable only in response to overloads above a predetermined value to increase the delay in such of said certain operations of said overload responsive means in which the overload occurs.

10. An automatic reclosing circuit breaker comprising, separable contacts, means having a part movable a predetermined distance in response to overloads on the circuit before automatically causing separation of said contacts to open the circuit, means operable in response to a circuit opening operation by said breaker to automatically close said contacts, dashpot means operable to delay movement of said movable part, a counting member advanced by closely successive operations of the breaker to increase the delay of the dashpot means braking means acting on the movable part in accordance with fluid pressure in the dashpot means during said period of increased delay to further retard movement of said movable part, and biasing means opposing operation of said braking means until the overload exceeds a predetermined value at which the operating force derived from the dashpot means exceeds the resisting force of the biasing means.

11. An automatic reclosing circuit breaker comprising separable contacts, means having part movable a predetermined distance in sponse to overloads on the circuit before automatically causing separation of said contacts to open the circuit, means responsive to a circuit opening operation by said breaker for automatically closing said contacts, means responsive t a predetermined operation in any series of closely successive operations for delaying a closely succeeding operation of said overload responsive 

